This invention relates to an electric connector for use in an electric circuit board unit and, in particular, to an electric connector which has a reduced thickness and a small size and which is capable of preventing electromagnetic interference (EMI) and electrostatic charge. This invention also relates to an electric circuit board unit with an electric connector of the type described.
A conventional electric circuit board unit comprises a frame, two electroconductive plates fixedly mounted on the frame, an electric circuit board located between the electroconductive plates and supported by the frame, and an electric connector attached to the frame. The electric connector comprises an insulator and a plurality of electroconductive contacts mounted on the insulator.
A CPU and/or a memory is mounted on the electric circuit board. In this connection, the electric circuit board unit is generally called an IC card or a memory card.
The electric circuit board unit is assembled in an electronic apparatus. At this time, the electric circuit board unit is connected through the electric connector to other circuit device mounted in the electronic apparatus. In order to provide protection against EMI or electrostatic charge, both electroconductive plates of the electric circuit board unit are connected to a ground terminal of the electronic apparatus in the interior of the electronic apparatus. Accordingly, the electric connector per se requires no protection against EMI. However, a troublesome wiring work is necessary for ground connection.
With recent development in multi-functional electronic apparatuses, it has been an increasing demand to further connect the electric circuit board unit with an external apparatus. For this purpose, another electric connector is additionally mounted in the electric circuit board unit. In this event, it is sometimes necessary to provide protection against EMI also for a combination of the other electric connector and the external apparatus. However, such protection is difficult if the other electric connector has a conventional structure. This is because it is impossible to connect both electroconductive plates of the electric circuit board unit and the ground terminal of the external apparatus without use of additional connection therebetween. Accordingly, a mating connector to be connected to the other electric connector must have a protecting structure against EMI. As a result, the mating connector inevitably has an increased size and an increased thickness.
In the meanwhile, each of the electric connector and the mating connector is provided with a coupling portion. The electric connector and the mating connector are connected when the respective coupling portions are coupled to each other. In order to avoid occurrence of a coupling error, the coupling portions have an eccentric structure so that they can be coupled only in a predetermined arrangement direction with respect to each other. Thus, coupling is inhibited in a false arrangement direction. However, if the electric connector has a reduced thickness, eccentricity of the coupling portions becomes small. This makes it difficult to provide a protecting structure against a coupling error.